Im only 15. Yes I'm sexually active. I looked at it an it looked like a bruise . I don't see a head to it so I know its not a boil. It hurts to walk sometimes or to lay on it. Ive been laying on a heating pad an its been helping.I had a fever the other day and I don't know if that could be some type of connection. It was swollen but its going down so should I keep putting hot compresses on it ?

You have a STD, you should probably go to the doctor immediately..